/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using PdfSharp.Pdf.IO;
using PdfSharp.Pdf.Security;
using PdfSharp.Pdf.Internal;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Represents a PDF trailer dictionary. Even trailers are dictionaries their never have a cross
  /// reference entry in PdfReferenceTable.
  /// </summary>
  internal sealed class PdfTrailer : PdfDictionary
  {
    /// <summary>
    /// Initializes a new instance of PdfTrailer.
    /// </summary>
    public PdfTrailer(PdfDocument document) : base(document)
    {
      this.document = document;
    }

    public int Size
    {
      get {return Elements.GetInteger(Keys.Size);}
      set {Elements.SetInteger(Keys.Size, value);}
    }

    // TODO: needed when linearized...
    //public int Prev
    //{
    //  get {return Elements.GetInteger(Keys.Prev);}
    //}

    public PdfDocumentInformation Info
    {
      get {return (PdfDocumentInformation)Elements.GetValue(PdfTrailer.Keys.Info, VCF.CreateIndirect);}
    }

    /// <summary>
    /// (Required; must be an indirect reference)
    /// The catalog dictionary for the PDF document contained in the file.
    /// </summary>
    public PdfCatalog Root
    {
      get {return (PdfCatalog)Elements.GetValue(PdfTrailer.Keys.Root, VCF.CreateIndirect);}
    }

    /// <summary>
    /// Gets the first or secound document identifier.
    /// </summary>
    public string GetDocumentID(int index)
    {
      if (index < 0 || index > 1)
        throw new ArgumentOutOfRangeException("index", "Index must be 0 or 1.");

      PdfArray array = Elements[Keys.ID] as PdfArray;
      if (array == null || array.Elements.Count < 2)
        return "";
      PdfItem item = array.Elements[index];
      if (item is PdfString)
        return ((PdfString)item).Value;
      return "";
    }

    /// <summary>
    /// Sets the first or secound document identifier.
    /// </summary>
    public void SetDocumentID(int index, string value)
    {
      if (index < 0 || index > 1)
        throw new ArgumentOutOfRangeException("index", "Index must be 0 or 1.");

      PdfArray array = Elements[Keys.ID] as PdfArray;
      if (array == null || array.Elements.Count < 2)
        array = CreateNewDocumentIDs();
      array.Elements[index] = new PdfString(value, PdfStringFlags.HexLiteral);
    }

    /// <summary>
    /// Creates and sets two identical new document IDs.
    /// </summary>
    internal PdfArray CreateNewDocumentIDs()
    {
      PdfArray array = new PdfArray(this.document);
      string id = PdfEncoders.RawEncoding.GetString(Guid.NewGuid().ToByteArray());
      array.Elements.Add(new PdfString(id, PdfStringFlags.HexLiteral));
      array.Elements.Add(new PdfString(id, PdfStringFlags.HexLiteral));
      Elements[Keys.ID] = array;
      return array;
    }

    /// <summary>
    /// Gets the standard security handler.
    /// </summary>
    public PdfStandardSecurityHandler SecurityHandler
    {
      get 
      {
        if (this.securityHandler == null)
          this.securityHandler = (PdfStandardSecurityHandler)Elements.GetValue(PdfTrailer.Keys.Encrypt, VCF.CreateIndirect);
        return this.securityHandler;
      }
    }
    internal PdfStandardSecurityHandler securityHandler;

    //internal override void WriteDictionaryElement(PdfSharp.Pdf.IO.PdfWriter writer, PdfName key)
    //{
    //  //if (key == Keys.ID)
    //  //{
    //  //  PdfArray array = Elements[key] as PdfArray;
    //  //  PdfItem item = array.Elements[0];
    //  //  //base.WriteDictionaryElement(writer, key);
    //  //  return;
    //  //}
    //  base.WriteDictionaryElement (writer, key);
    //}

    internal override void WriteObject(PdfWriter writer)
    {
      // Delete /XRefStm entry, if any
      this.elements.Remove(Keys.XRefStm);

      // Don't encypt myself
      PdfStandardSecurityHandler securityHandler = writer.SecurityHandler;
      writer.SecurityHandler = null;
      base.WriteObject(writer);
      writer.SecurityHandler = securityHandler;
    }

    /// <summary>
    /// Replace temporary irefs by their correct counterparts from the iref table.
    /// </summary>
    internal void Finish()
    {
      // \Root
      PdfReference iref = document.trailer.Elements[PdfTrailer.Keys.Root] as PdfReference;
      if (iref != null && iref.Value == null)
      {
        iref = document.irefTable[iref.ObjectID];
        Debug.Assert(iref.Value != null);
        this.document.trailer.Elements[PdfTrailer.Keys.Root] = iref;
      }

      // \Info
      iref = this.document.trailer.Elements[PdfTrailer.Keys.Info] as PdfReference;
      if (iref != null && iref.Value == null)
      {
        iref = document.irefTable[iref.ObjectID];
        Debug.Assert(iref.Value != null);
        this.document.trailer.Elements[PdfTrailer.Keys.Info] = iref;
      }

      // \Encrypt
      iref = this.document.trailer.Elements[PdfTrailer.Keys.Encrypt] as PdfReference;
      if (iref != null)
      {
        iref = document.irefTable[iref.ObjectID];
        Debug.Assert(iref.Value != null);
        this.document.trailer.Elements[PdfTrailer.Keys.Encrypt] = iref;

        // The encryption dictionary (security handler) was read in before the XRefTable construction 
        // was completed. The next lines fix that state (it take several hours to find that bugs...).
        iref.Value = this.document.trailer.securityHandler;
        this.document.trailer.securityHandler.Reference = iref;
        iref.Value.Reference = iref;
      }

      Elements.Remove(Keys.Prev);

      this.document.irefTable.IsUnderConstruction = false;
    }

    /// <summary>
    /// Predefined keys of this dictionary.
    /// </summary>
    internal sealed class Keys : KeysBase
    {
      /// <summary>
      /// (Required; must not be an indirect reference) The total number of entries in the file�s 
      /// cross-reference table, as defined by the combination of the original section and all
      /// update sections. Equivalently, this value is 1 greater than the highest object number
      /// used in the file.
      /// Note: Any object in a cross-reference section whose number is greater than this value is
      /// ignored and considered missing.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string Size = "/Size";

      /// <summary>
      /// (Present only if the file has more than one cross-reference section; must not be an indirect
      /// reference) The byte offset from the beginning of the file to the beginning of the previous 
      /// cross-reference section.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Optional)]
      public const string Prev = "/Prev";

      /// <summary>
      /// (Required; must be an indirect reference) The catalog dictionary for the PDF document
      /// contained in the file.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Required, typeof(PdfCatalog))]
      public const string Root = "/Root";

      /// <summary>
      /// (Required if document is encrypted; PDF 1.1) The document�s encryption dictionary.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Optional, typeof(PdfStandardSecurityHandler))]
      public const string Encrypt = "/Encrypt";

      /// <summary>
      /// (Optional; must be an indirect reference) The document�s information dictionary.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Optional, typeof(PdfDocumentInformation))]
      public const string Info = "/Info";

      /// <summary>
      /// (Optional, but strongly recommended; PDF 1.1) An array of two strings constituting
      /// a file identifier for the file. Although this entry is optional, 
      /// its absence might prevent the file from functioning in some workflows
      /// that depend on files being uniquely identified.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string ID = "/ID";

      /// <summary>
      /// (Optional) The byte offset from the beginning of the file of a cross-reference stream.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Optional)]
      public const string XRefStm = "/XRefStm";

      /// <summary>
      /// Gets the KeysMeta for these keys.
      /// </summary>
      public static DictionaryMeta Meta
      {
        get
        {
          if (Keys.meta == null)
            Keys.meta = CreateMeta(typeof(Keys));
          return Keys.meta;
        }
      }
      static DictionaryMeta meta;
    }

    /// <summary>
    /// Gets the KeysMeta of this dictionary type.
    /// </summary>
    internal override DictionaryMeta Meta
    {
      get {return Keys.Meta;}
    }
  }
}
